The electrical and magnetic properties of nanocrystalline binary Fe100-xNix alloys, where x ranges from 0 to 100, prepared by a combination of aqueous and solid-state reduction processes have been ...studied vis-a-vis their microstructure. The microstructural studies indicate the formation of near-equilibrium phases in the alloys with crystallite size in the range 20-40nm. The crystallite size in the case of pure Fe and Ni, however, is in the range 40-80nm. The electrical transport in the temperature range 20-300K exhibits a typical ferromagnetic metallic behavior in all the cases and the absolute resistivity of nanocrystalline Fe100-xNix alloys decreases monotonically with increasing Ni content. The saturation magnetization of the alloys on the other hand decreases progressively with Ni addition towards that of pure Ni value. The coercivity of alloys is found to be independent of temperature in the range 5-300K except in the case of pure Ni wherein it increases from 30Oe at 300K to 65Oe at 5K. The electrical and magnetic properties of the nanocrystaline Fe-Ni alloys do not follow the predictions of simple itinerant band model for alloys. The temperature dependence of saturation magnetization in all the cases has a T3/2 Bloch variation while the average atomic moment of the alloys has an effective medium composition dependence.
We have applied the non-extensive statistical mechanics to free electrons in several metals to calculate the electronic specific heat at low temperature. In this case, the Fermi–Dirac (FD) function ...is modified from its Boltzmann–Gibbs (BG) form, with the exponential part going to a q-exponential, in its non-extensive form. In most cases, the non-extensive parameter, q, is found to be greater than unity to produce the correct thermal effective mass, m∗, of electrons. The ratio m∗∕m is found to show a nice systematic dependence on q. Results indicate, electrons in metals, in the presence of long range correlations are reasonably well described by Tsallis statistics.
•Tsallis non-extensive statistics has been used in a thermodynamically consistent approach to determine electronic specific heat, CV, in metals.•The ratio of the thermal effective mass to the free electron mass, (m∗∕m), for all metals considered, show a universal trend in terms of the non-extensive parameter, q.
The electrical and magnetic properties of nanocrystalline binary Fe
100−
x
Ni
x
alloys, where
x ranges from 0 to 100, prepared by a combination of aqueous and solid-state reduction processes have ...been studied vis-à-vis their microstructure. The microstructural studies indicate the formation of near-equilibrium phases in the alloys with crystallite size in the range 20–40
nm. The crystallite size in the case of pure Fe and Ni, however, is in the range 40–80
nm. The electrical transport in the temperature range 20–300
K exhibits a typical ferromagnetic metallic behavior in all the cases and the absolute resistivity of nanocrystalline Fe
100−
x
Ni
x
alloys decreases monotonically with increasing Ni content. The saturation magnetization of the alloys on the other hand decreases progressively with Ni addition towards that of pure Ni value. The coercivity of alloys is found to be independent of temperature in the range 5–300
K except in the case of pure Ni wherein it increases from 30
Oe at 300
K to 65
Oe at 5
K. The electrical and magnetic properties of the nanocrystaline Fe–Ni alloys do not follow the predictions of simple itinerant band model for alloys. The temperature dependence of saturation magnetization in all the cases has a
T
3/2 Bloch variation while the average atomic moment of the alloys has an effective medium composition dependence.
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